Laptop

This article may require copy editing for grammar, style, cohesion, tone, or spelling. You can assist by editing it.(June 2015)

A laptop or a notebook is a portable personal computer with a clamshell form factor, suitable for mobile use.[1] Although there used to be a distinction between laptops and notebooks (the former were bigger and heavier than the latter), there is often no longer any difference in practice. [2] Laptops are commonly used in a variety of settings, including at work, in education, and for personal multimedia.

A laptop combines the components and inputs of a desktop computer, including display, speakers, keyboard and pointing device (such as a touchpad or a trackpad) into a single device. Most modern-day laptops also have an integrated webcam and a microphone. A laptop can be powered either from a rechargeable battery, or by mains electricity via an AC adapter. Laptop is a diverse category of devices and other more specific terms, such as rugged notebook or convertible, refer to specialist types of laptops, which have been optimized for specific uses. Hardware specifications change significantly between different types, makes and models of laptops.

Portable computers, which later developed into modern laptops, were originally considered to be a small niche market, mostly for specialized field applications, such as the military, accountancy, for sales representatives etc. As portable computers developed and became more like modern laptops, becoming smaller, lighter, cheaper, and more powerful, they became very widely used for a variety of purposes.[3]

The terms laptop and notebook are used fairly interchangeably to describe a portable computer in English, although in some parts of the world one or the other may be preferred. There is some question as to the original etymology and specificity of either term—the term laptop appears to have been coined in the early 1980s to describe a mobile computer which can be used on one's lap, and to distinguish these devices from earlier, much heavier, portable computers (often called "luggables" in retrospect). The term "notebook" appears to have gained currency somewhat later as manufacturers started producing even smaller portable devices, further reducing their weight and size and incorporating a display roughly the size of A4 paper; these were marketed as notebooks to distinguish them from bulkier laptops.[4] Regardless of the etymology, by the late 1990s, the terms were interchangeable.

As the personal computer (PC) became feasible in 1971, the idea of a portable personal computer followed. A "personal, portable information manipulator" was imagined by Alan Kay at Xerox PARC in 1968,[5] and described in his 1972 paper as the "Dynabook".[6]

The IBM Special Computer APL Machine Portable (SCAMP), was demonstrated in 1973. This prototype was based on the IBM PALM processor (Put All Logic in Microcode or 128 bit).[7]

The IBM 5100, the first commercially available portable computer, appeared in September 1975, and was based on the SCAMP prototype.[8]

As 8-bit CPU machines became widely accepted, the number of portables increased rapidly. The Osborne 1, released in 1981, used the Zilog Z80 and weighed 23.6 pounds (10.7 kg). It had no battery, a 5 in (13 cm) CRT screen, and dual 5.25 in (13.3 cm) single-density floppy drives. In the same year the first laptop-sized portable computer, the Epson HX-20, was announced.[9] The Epson had a LCD screen, a rechargeable battery, and a calculator-size printer in a 1.6 kg (3.5 lb) chassis. Both Tandy/RadioShack and HP also produced portable computers of varying designs during this period.[10][11]

The first laptops using the flip form factor appeared in the early 1980s. The Dulmont Magnum was released in Australia in 1981–82, but was not marketed internationally until 1984–85. The US$8,150 (US$19,920 today) GRiD Compass 1100, released in 1982, was used at NASA and by the military among others. The Gavilan SC, released in 1983, was the first computer described as a "laptop" by its manufacturer.[12] From 1983 onward, several new input techniques were developed and included in laptops, including the touchpad (Gavilan SC, 1983), the pointing stick (IBM ThinkPad 700, 1992) and handwriting recognition (Linus Write-Top,[13] 1987). Some CPUs, such as the 1990 Intel i386SL, were designed to use minimum power to increase battery life of portable computers, and were supported by dynamic power management features such as Intel SpeedStep and AMD PowerNow! in some designs.

Displays reached VGA resolution by 1988 (Compaq SLT/286), and colour screens started becoming a common upgrade in 1991 with increases in resolution and screen size occurring frequently until the introduction of 17"-screen laptops in 2003. Hard drives started to be used in portables, encouraged by the introduction of 3.5" drives in the late 1980s, and became common in laptops starting with the introduction of 2.5" and smaller drives around 1990; capacities have typically lagged behind physically larger desktop drives. Optical storage, read-onlyCD-ROM followed by writeable CD and later read-only or writeable DVD and Blu-ray, became common in laptops early in the 2000s.

Since the introduction of portable computers during late 70s, their form has seriously changed over decades, spawning a variety of visually and technologically differing subclasses. Except where there is a distinct legal trademark around the term (notably Ultrabook) there are rarely hard lines between these terms, and their usage has varied over time and between different sources.

The form of a traditional laptop computer is a clamshell, with a screen on one of its inner sides and a keyboard on the opposite. It can be easily folded to conserve space while traveling. The screen and keyboard are inaccessible while closed. Devices of this form are commonly called a 'traditional laptop' or notebook, particularly if they have a screen size of 13 to 17 inches measured diagonally and run a full-featured operating system like Windows 8.1, OS X or Linux. Traditional laptops are the most common form of laptops, although Chromebooks, Ultrabooks, convertibles and laplets (described below) are becoming more common, with similar performance being achieved in their more portable or affordable forms.

A subnotebook or an ultraportable is a laptop designed and marketed with an emphasis on portability (small size, low weight and often longer battery life). Subnotebooks are usually smaller and lighter than standard laptops, weighing between 0.8 and 2 kg (2 to 5 pounds),[14] with a battery life, exceeding 10 hours.[15] Since the introduction of netbooks and ultrabooks, the line between subnotebooks and either category has been blurry. Netbooks are, in essence, a more basic-featured and a cheap subcategory of subnotebooks, and while some ultrabooks have a screen size too large to qualify as subnotebooks, certain ultrabooks fit in a subnotebook category. One notable example of a subnotebook is Apple Macbook Air.

Netbook was a form of a laptop as inexpensive, light-weight, energy-efficient device, especially suited for wireless communication and Internet access.[16][17] Netbooks first became commercially available in around 2008 on the market, featuring a weight, a display size and a price combination of < 1 kg, < 9" and < U.S. $400 respectively. The name netbook (with net short for Internet) is used as "the device excels in web-based computing performance".[18] To begin with, netbooks were mostly sold with light-weight variants of the Linux operating system, although later versions often have Windows XP or Windows 7 operating systems. The term "netbook" is largely a dead one; as of the end of 2012, no machines marketed as netbooks remained for sale,[19] although machines that would have once been called netbooks—small, inexpensive, and low powered—never ceased being sold, in particular the smaller Chromebook models.

Typical modern convertibles have a complex joint between the keyboard housing and the display permitting the display panel to swivel and then lie flat on the keyboard housing. Most convertibles feature a touchscreen display alongside the traditional touchpad, to work in a tablet mode. The convertibles fit both in laptop and tablet device categories, but usually considered laptops, due to increased size and weight over the mainstream tablets.

The single joint used to enable the rotate and swivel motion of the screen creates a physical point of weakness on the laptop. Some manufacturers have attempted to overcome these weak points by adopting innovative methods such as a sliding design in which the screen slides up from the slate-like position and locks into place to provide the laptop mode. Due to the design of convertibles, they have few other weaknesses over traditional laptops, although a smaller form is often desired to increase portability.

The most recent laptop device category is a laplet. It is a portmanteau of the words laptop and tablet and it is a crossover of these device types.[20] Although being typically considered as a tablet (by such agencies as FAA and TSA), laplets share certain similarities to laptops, and may be considered as its alternative form. Laplets are often marketed as a laptop replacement tablets.

Its specification is most closely resembles one of an Ultrabook, but laplet is made of two distinct parts, offering a touchscreen display which can be separated from the keyboard. Laplets are often very thin (around 10 mm) and light devices with a long battery life. Compared to mainstream tablets, laplets can be distinguished from them as they feature an x86-architecture CPU (typically low- or ultra-low-voltage model), such as Intel Core i5, run a full-featured OS like Windows 8.1, and have a number of typical laptop I/O ports, such as USB and Mini DisplayPort.

Laplets are designed to be used not only as a media consumption device, but also as a valid desktop or laptop replacement due to their ability to run desktop applications, such as Adobe Photoshop, connect multiple peripheral devices, such as a mouse, keyboard and a number of external displays.[21]

A desktop-replacement laptop is a class of large device, which is not intended primarily for mobile use. They are bulkier and not as portable as other laptops, and are intended for use as compact and transportable alternatives to a desktop computer.[22] Desktop replacements are larger and typically heavier than other classes of laptops. They are capable of containing more powerful components and have a 15-inch or larger display.[22]

Desktop replacement laptops' operation time on batteries is typically shorter than other laptops, in rare cases they have no battery at all. In the past, some laptops in this class used a limited range of desktop components to provide better performance for the same price at the expense of a battery life, although the practice has largely died out.[23]

The names Media Center Laptops and Gaming Laptops are used to describe specialized notebook computers, often overlapping with the desktop replacement form factor.[14]

A rugged laptop is designed to reliably operate in harsh usage conditions such as strong vibrations, extreme temperatures, and wet or dusty environments. Rugged laptops are usually designed from scratch, rather than adapted from regular consumer laptop models. Rugged laptops are bulkier, heavier, and much more expensive than regular laptops,[24] and thus are seldom seen in regular consumer use.

The design features found in rugged laptops include a rubber sheeting under keyboard keys, a sealed port and connector covers, a passive cooling, very bright displays, easily readable in daylight, cases and frames made of magnesium alloys that are much stronger, than plastic found in commercial laptops and solid-state storage devices or hard disc drives, that are shock mounted to withstand constant vibrations. Rugged laptops are commonly used by public safety services (police, fire and medical emergency), military, utilities, field service technicians, construction, mining and oil drilling personnel. Rugged laptops are usually sold to organizations, rather than individuals, and are rarely marketed via retail channels.

The basic components of laptops function identically to their desktop counterparts. Traditionally they were miniaturized and adapted to mobile use, although as of the present decade an increasing number of desktop systems use the same smaller, lower-power parts which originally evolved for mobile use. The design bounds on power, size, and cooling of laptops limit the maximum performance of laptop parts compared to that of desktop components, although that difference has increasingly narrowed over recent years.

In general, laptop components are not intended to be replaceable. A few, such as processors, follow their own standards but are difficult to replace because of other factors (for example, in the case of processors cooling and access limitations can make upgrades very difficult or impossible). In a very compact laptop, such as laplets, there may be no upgradeable components at all.[25]

Most modern laptops feature a 13 inches (33 cm) or larger color active matrix displays based on LED lighting with resolutions of 1280×800 (16:10) or 1366×768 (16:9) pixels and above. Models with LED-based lighting offer lesser power consumption, and often higher brightness. Netbooks with a 10 inches (25 cm) or smaller screen typically use a resolution of 1024×600, while netbooks and subnotebooks with a 11.6 inches (29 cm) or 12 inches (30 cm) screen use standard notebook resolutions. Having a higher resolution display may allow more items to fit onscreen at a time, improving the user's ability to multitask, although at the higher resolutions on smaller screens, the resolution may only serve to display sharper graphics and text rather than increasing the usable area. Since the introduction of the MacBook Pro with Retina display in 2012, there has been an increase in the availability of very-high resolution (1920×1080 and higher) displays, even in relatively small systems, and in typical 15-inch screens resolutions as high as 3200×1800 are available.

External displays can be connected to most laptops, and models with Mini DisplayPort can handle up to three.[28]

A laptop's central processing unit (CPU) has advanced power-saving features and produces less heat, than one intended purely for desktop use. Typically laptop CPU have two processor cores, although 4-core models are also available. For low price and mainstream performance, there is no longer a significant performance difference between laptop and desktop CPUs, but at the high end the fastest 4-to-8-core desktop CPUs are still substantially outperform the fastest 4-core laptop processors, at the expense of massively higher power utilization and heat generation — the fastest laptop processors top out at 56 watts of heat, while the fastest desktop processors top out at 150 watts.

There have been a wide range of CPUs designed for laptops available from both Intel, AMD and other manufacturers. On non-x86 architectures, Motorola and IBM produced the chips for the former PowerPC-based Apple laptops (iBook and PowerBook). Many laptops have removable CPUs, although this has become less common in the past few years as the trend has been to increasingly thin and light models. In other laptops the CPU is soldered on the motherboard and is non-replaceable, this is nearly universal in ultrabooks, for example.

In the past, some laptops have used a desktop processor instead of the laptop version and have high performance gains at the cost of greater weight, heat and limited battery life. The practice is largely extinct as of 2013.

Unlike their desktop counterparts, laptop CPUs are nearly impossible to overclock. A thermal operating mode of laptops is very close to its limits and there is almost no headroom for an overclocking related operating temperature increase. A possibility to improve a cooling system of a laptop to allow overclocking is extremely rare.

On most laptops a graphical processing unit (GPU) is integrated into the CPU to conserve power and space. This was introduced by Intel with the Core i-series of mobile processors in 2010, and similar APU processors by AMD later that year. Prior to that, lower-end machines tended to use graphics processors integrated to the system chipset, while higher end machines had a separate graphics processor. In the past, laptops lacking a separate graphics processor were limited in their utility for gaming and professional applications involving 3D graphics, but the capabilities of CPU-integrated graphics has converged with the low-end of dedicated graphics processors in the past few years. Higher-end laptops intended for gaming or professional 3D work still come with dedicated, in some cases even dual, graphics processors on the motherboard or as an internal expansion card. Since 2011, these almost always involve switchable graphics so that when there is not demand for the higher performance dedicated graphics processor, the more power-efficient integrated graphics processor will be used. Nvidia Optimus is an example of this sort of system of switchable graphics.

Most laptops use SO-DIMMmemory modules, these are about half the size of desktop DIMMs.[27] They may be accessible from the bottom of the laptop for ease of upgrading, or placed in locations not intended for user replacement. Most laptops have two memory slots, although some of the lowest-end will have only one, and some high end models (usually mobile engineering workstations, and a few high-end models intended for gaming) have four. Most mid-range laptops are factory equipped with 4–6 GB of RAM. Netbooks are commonly equipped with only 1–2 GB of RAM and generally only expandable to 2 GB, if at all. Because of the limitation of DDR3 SO-DIMM to a maximum of 8 GB per module, this means most laptops can only be expanded to a total of 16 GB of memory, until systems using DDR4 memory start becoming available.

Laptops may have a memory soldered to a motherboard to conserve space, to allow a thinner chassis design, and improve security, if a system is equipped with a trusted platform module (TPM), which requires memory soldering to prevent cold boot attack.[29] Soldered memory cannot be upgraded.

Traditionally laptops had a hard disk drive (HDD) as a main non-volatile storage, but it proved inefficient for use in mobile devices due to a high power consumption, heat production and a presence of moving parts, which can cause damage to both the drive itself and the data stored, when a laptop is unstable physically, e.g. during its use while transporting it or after its accidental drop. With the advent of flash memory technology, most mid- to high-end laptops opted to a more compact, power efficient and fast solid-state drives (SSD), which eliminated a hazard of a drive and data corruption, caused by a laptop physical impacts.[30] A solid-state drive (SSD) is one of the most effective upgrades to make in a laptop and an excellent choice for a primary system disk. With their superior read and write speeds, they can instantly make operating system more responsive. Boot up and shut down times are signiﬁcantly shorter as compared to mechanical disk, and applications will typically open much faster.[31] In most low-end laptops however, HDDs are still dominating, due to their significantly lower cost.

Most laptops use 2.5-inch drives, which are a smaller version of a 3.5-inch desktop drive form factor. 2.5-inch HDDs are more compact, power efficient and produce less heat, while at the same time have lesser capacity and a data transfer rate. For SSDs however, these miniaturization related trade-offs are non-existent, because SSDs' internal parts were initially designed to have very small footprint. Some very compact laptops support even smaller 1.8-inch HDDs. SSDs feature a traditional 2.5- or 1.8-inch or a laptop-specific mSATA or M.2 card's form factor.

SSDs have a better data transfer rate, power consumption and a failure rate,[32][33][34] compared to HDDs. However, the latter have a significantly better cost per capacity and are more spacious. As of 2014, speaking of 2.5-inch form factor, maximum single HDD's capacity is 2 TB, whereas SSDs are a 1 TB maximum.

Most laptops can contain a single 2.5-inch drive, while a small number of laptops with a screen, wider than 17 inches, can house a pair. Some laptops support a hybrid mode, combining a 2.5-inch drive, typically a spacious HDD for data, with a mSATA or M.2 drive, typically less capacitive, but significantly faster SSD with operating system partition for increasing laptop I/O performance. Another way to increase performance is to use a smaller SSD of 16-32 GB as a cache drive in a compatible OS.

Some laptops may have a very limited drive upgradeability when SSD has a non-standard shape and/or require a proprietary daughter card.[35]

Some laptops have a very limited space on the installed SSD, relying on availability of cloud storage services for storing of user data. Chromebook laptops is a prominent example of this approach.

A variety of external HDDs or NAS data storage servers with support of RAID technology can be attached to virtually any laptop over such interfaces as USB, FireWire, eSATA, Thunderbolt or over a wired or wireless network to further increase space for storage of data.

CD/DVD/BDoptical disc drive was nearly universal on full-sized models, and it remains fairly common for now in laptops with a screen wider than 15 inches (38 cm), although the trend towards thinner and lighter machines is gradually eliminating it. It is very uncommon in compact laptops, such as subnotebooks and netbooks. Laptop optical drives tend to follow a standard form factor, and usually have a standard mSATA connector. It is often possible to replace an optical drive with a newer model. In certain laptop models there is a possibility to replace an optical drive with a second hard drive, using a caddy that fills the extra space the optical drive would have occupied.

A pointing stick, touchpad or both are used to control the position of the cursor on the screen, and an integrated keyboard[36] is used for typing. An external keyboard and/or mouse may be connected using USB port, or wirelessly, e.g. via Bluetooth. With the advent of ultrabooks and support of touch input by recent operating systems, such as Windows 8.1, multitouchtouchscreen display is a common feature of a modern laptop.

On a typical laptop there are several USBports, an external monitor port (VGA, DVI, HDMI or Mini DisplayPort), audio in/out (often in form of a single socket) are common. It's possible to connect up to three external displays to a modern laptop via a single Mini DisplayPort, utilizing a multi-stream transport technology.[28]

Apple, in a 2015 version of its MacBook, transitioned from a number of different I/O ports to a single USB-C port.[37] This port can be used both for charging and connecting variety of devices through the use of aftermarket adapters. Google, with its updated version of Chromebook Pixel, shows a similar transition trend towards USB-C, although keeping an older USB-A ports for a better compatibility with older devices.[38]

In the past, a PC Card (formerly PCMCIA) or ExpressCard slot for expansion cards was often present on laptops to allow adding and removing functionality, even when the laptop is powered on, these are becoming increasingly rare since the introduction of USB 3.0. Some internal subsystems such as: ethernet, Wi-Fi, or a Wireless cellular modem can be implemented as replaceable internal expansion cards, usually accessible under an access cover on the bottom of the laptop. The standards for such cards is PCI Express, which comes in both mini and even smaller M.2 sizes. In newer laptops it is not uncommon to also see Micro SATA (mSATA) functionality on PCI Express Mini or M.2 card slots allowing the use of those slots for SATA-based solid state drives.[39]

Current laptops utilize lithium ionbatteries, with some thinner models using the flatter lithium polymer technology. These two technologies have largely replaced the older nickel metal-hydride batteries. Battery life is highly variable by model and workload, and can range from one hour to nearly a day. A battery's performance gradually decreases over time, substantial reduction in capacity is typically evident after one to three years of regular use, depending on the charging and discharging pattern and the design of the battery. Innovations in laptops and batteries have seen situations which the battery can provide up to 24 hours of continued operation, assuming average power consumption levels. An example is the HP EliteBook 6930p when used with its ultra-capacity battery.[40]

Laptop's battery is charged using an external power supply, which outputs a DC voltage typically in the range of 7.2—24 volts. The power supply is usually external, and connected to the laptop through a DC connector cable. In most cases it can charge the battery and power the laptop simultaneously. When the battery is fully charged, the laptop continues to run on power supplied by the external power supply, avoiding a battery use. Battery charges in a shorter period of time if laptop is turned off or sleeping. The charger typically adds about 400 grams (0.88 lb) to the overall transporting weight of a laptop, although some models are substantially heavier or lighter.

Waste heat from operation is difficult to remove in the compact internal space of a laptop. Early laptops used heat sinks placed directly on the components to be cooled, but when these hot components are deep inside the device, a large space-wasting air duct is needed to exhaust the heat. Modern laptops instead rely on heat pipes to rapidly move waste heat towards the edges of the device, to allow for a much smaller and compact fan and heat sink cooling system. Waste heat is usually exhausted away from the device operator, towards the rear or sides of the device. Multiple air intake paths are used since some intakes can be blocked, such as when the device is placed on a soft conforming surface like a chair cushion. It is believed that some designs with metal cases, like Apple's aluminum MacBook Pro and MacBook Air, also employ the case of the machine as a heat sink, allowing it to supplement cooling by dissipating heat out of the device core. Secondary device temperature monitoring may reduce performance or trigger an emergency shutdown if it is unable to dissipate heat, such as if the laptop were to be left running and placed inside a carrying case. Such a condition has the potential to melt plastics or ignite a fire.

Aftermarket cooling pads can be used with most laptops to further improve temperature operating conditions.

A docking station (sometimes referred to simply as a dock) is a laptop accessory that contains multiple ports, and in some cases also expansion slots and/or bays for fixed or removable drives. A laptop connects and disconnects easily to a docking station, typically through a single large proprietary connector.

Docking station is an especially popular laptop accessory in a corporate computing environment, due to a possibility of a docking station to transform a laptop into a full-featured desktop replacement, yet to allow for its easy release, which can be advantageous to road warrior employees.

If just more number of existing ports needed, or their position on a laptop is inconvenient, one can use a more cheaper passive device, a port replicator. These devices simply mates to the connectors on the back of the laptop, or connects via a standardized port such as USB or FireWire.

Laptop charging trolleys, also known as laptop trolleys or laptop carts, are mobile storage containers to charge laptops, netbooks and tablet computers all together. The trolleys are predominantly used in schools that have replaced their traditional static ICT[41] suites of desktop computers with laptops, but do not have enough plug sockets in their buildings to charge all of the devices.

The trolleys can be wheeled between rooms and classrooms so that anyone in a particular building can access fully chargedIT equipment.[42]

Laptop charging trolleys are also used to deter and protect against opportunistic and organized theft. Schools, especially those with open plan designs, are often prime targets for thieves and laptops, netbooks and tablets can easily be concealed and removed from buildings. Laptop charging trolleys were designed and constructed to protect against theft. They are generally made out of steel, and the laptops remain locked up while not in use. Although the trolleys can be moved between areas in buildings, they can often also be mounted to the floor or walls to prevent thieves walking off with investments, especially overnight.[41]

In some laptops, solar panels are able to generate enough solar power for the laptop to operate.[43] The One Laptop Per Child Initiative released the OLPC XO-1 laptop which was tested and successfully operated by use of solar panels.[44] Presently, they are designing a OLPC XO-3 laptop with these features. The OLPC XO-3 can operate with 2 Watts of electricity because its renewable energy resources generate a total of 4 Watts.[45][46]Samsung has also designed a NC215S Solar powered notebook that will be sold commercially in the US market.[47]

Portability is usually the first feature mentioned in any comparison of laptops versus desktop PCs.[48] Physical portability allows that a laptop can be used in many places— not only at home and at the office, but also during commuting and flights, in coffee shops, in lecture halls and libraries, at clients' location or at a meeting room, etc. The portability feature offers several distinct advantages:

Productivity: Using a laptop in places where a desktop PC can not be used, and at times that would otherwise be wasted. For example, an office worker managing their e-mails during an hour-long commute by train, or a student doing his/her homework at the university coffee shop during a break between lectures.[49]

Immediacy: Carrying a laptop means having instant access to various information, personal and work files. Immediacy allows better collaboration between coworkers or students, as a laptop can be flipped open to present a problem or a solution anytime, anywhere.

Up-to-date information: If a person has more than one desktop PC, a problem of synchronization arises: changes made on one computer are not automatically propagated to the others. There are ways to resolve this problem, including physical transfer of updated files (using a USB flash memory stick or CDRs) or using synchronization software over the Internet. However, using a single laptop at both locations avoids the problem entirely, as the files exist in a single location and are always up-to-date.

Connectivity: A proliferation of Wi-Fi wireless networks and cellular broadband data services (HSDPA, EVDO and others) combined with a near-ubiquitous support by laptops[50] means that a laptop can have easy Internet and local network connectivity while remaining mobile. Wi-Fi networks and laptop programs are especially widespread at university campuses.[51]

Other advantages of laptops:

Size: Laptops are smaller than desktop PCs. This is beneficial when space is at a premium, for example in small apartments and student dorms. When not in use, a laptop can be closed and put away.

Low power consumption: Laptops are several times more power-efficient than desktops. A typical laptop uses 20–120 W, compared to 100–800 W for desktops. This could be particularly beneficial for businesses (which run hundreds of personal computers, multiplying the potential savings) and homes where there is a computer running 24/7 (such as a home media server, print server, etc.)

Quiet: Laptops are often quieter than desktops, due both to the components (quieter, slower 2.5-inch hard drives) and to less heat production leading to use of fewer and slower cooling fans.

Battery: a charged laptop can continue to be used in case of a power outage and is not affected by short power interruptions and blackouts. A desktop PC needs a UPS to handle short interruptions, blackouts and spikes; achieving on-battery time of more than 20–30 minutes for a desktop PC requires a large and expensive UPS.[52]

All-in-One: designed to be portable, laptops have everything integrated into the chassis. For desktops (excluding all-in-ones) this is divided into the desktop, keyboard, mouse, display, and optional peripherals such as speakers.

While the performance of mainstream desktops and laptop is comparable, and the cost of laptops has fallen less rapidly than desktops, laptops remain more expensive than desktop PCs at the same performance level.[53] The upper limits of performance of laptops remain much lower than the highest-end desktops (especially "workstation class" machines with two processor sockets), and "bleeding-edge" features usually appear first in desktops and only then, as the underlying technology matures, are adapted to laptops.

For Internet browsing and typical office applications, where the computer spends the majority of its time waiting for the next user input, even relatively low-end laptops (such as Netbooks) can be fast enough for some users.[54] As of mid-2010, at the lowest end, the cheapest netbooks—between US$200–300—remain more expensive than the lowest-end desktop computers (around US$200) only when those are priced without a screen/monitor. Once an inexpensive monitor is added, the prices are comparable.

Most higher-end laptops are sufficiently powerful for high-resolution movie playback, some 3D gaming and video editing and encoding. However, laptop processors can be disadvantaged when dealing with higher-end database, maths, engineering, financial software, virtualization, etc.This is because laptops use the mobile versions of processors to conserve power, and these lag behind desktop chips when it comes to performance.[55] Also, the top-of-the-line mobile graphics processors (GPUs) are significantly behind the top-of-the-line desktop GPUs to a greater degree than the processors, which limits the utility of laptops for high-end 3D gaming and scientific visualization applications.

Some manufacturers work around this performance problem by using desktop CPUs for laptops.[56]

Upgradeability of laptops is very limited compared to desktops, which are thoroughly standardized. In general, hard drives and memory can be upgraded easily. Optical drives and internal expansion cards may be upgraded if they follow an industry standard, but all other internal components, including the motherboard, CPU and graphics, are not always intended to be upgradeable. Intel, Asus, Compal, Quanta and some other laptop manufacturers have created the Common Building Block standard for laptop parts to address some of the inefficiencies caused by the lack of standards.

The reasons for limited upgradeability are both technical and economic. There is no industry-wide standard form factor for laptops; each major laptop manufacturer pursues its own proprietary design and construction, with the result that laptops are difficult to upgrade and have high repair costs. With few exceptions, laptop components can rarely be swapped between laptops of competing manufacturers, or even between laptops from the different product-lines of the same manufacturer.

Some upgrades can be performed by adding external devices, either USB or in expansion card format such as PC Card. Devices such as sound cards, network adapters, hard and optical drives, and numerous other peripherals are available, but these upgrades usually impair the laptop's portability, because they add cables and boxes to the setup and often have to be disconnected and reconnected when the laptop is on the move.

Because of their small and flat keyboard and trackpad pointing devices, prolonged use of laptops can cause repetitive strain injury.[57] Usage of separate, external ergonomic keyboards and pointing devices is recommended to prevent injury when working for long periods of time; they can be connected to a laptop easily by USB or via a docking station. Some health standards require ergonomic keyboards at workplaces.

The integrated screen often requires users to lean over for a better view, which can cause neck and/or spinal injuries. A larger and higher-quality external screen can be connected to almost any laptop to alleviate that and to provide additional screen space for more productive work. Another solution is to use a computer stand.

For anyone not buying a new screen, a simple method to reduce risk of spinal injury is to position the laptop's screen in a manner that an obtuse angle (more than 90 degrees open) is formed. It is then possible for the neck to remain straight during use of the device.

A study by State University of New York researchers found that heat generated from laptops can increase the temperature of the lap of male users when balancing the computer on their lap, potentially putting sperm count at risk. The study, which included roughly two dozen men between the ages of 21 and 35, found that the sitting position required to balance a laptop can increase scrotum temperature by as much as 2.1 °C (3.78 °F). However, further research is needed to determine whether this directly affects male sterility.[58]

A 2010 study of 29 males published in Fertility and Sterility found that men who kept their laptops on their laps experienced scrotal hyperthermia (overheating) in which their scrotal temperatures increased by up to 2 °C. The resulting heat increase, which could not be offset by a laptop cushion, may increase male infertility.[59][60][61][62][63]

A common practical solution to this problem is to place the laptop on a table or desk, or to use a book or pillow between the body and the laptop.[citation needed] Another solution is to obtain a cooling unit for the laptop. These are usually USB powered and consist of a hard thin plastic case housing one, two or three cooling fans – with the entire assembly designed to sit under the laptop in question – which results in the laptop remaining cool to the touch, and greatly reduces laptop heat buildup.[citation needed]

Because of their portability, laptops are subject to more wear and physical damage than desktops. Components such as screen hinges, latches, power jacks and power cords deteriorate gradually from ordinary use. A liquid spill onto the keyboard, a rather minor mishap with a desktop system, can damage the internals of a laptop and result in a costly repair. One study found that a laptop is three times more likely to break during the first year of use than a desktop.[68]

In order to help maintain a laptop, it is recommended to clean a laptop every three months for dirt, debris, dust, and food particles. Most cleaning kits consist of a lint-free or Microfiber cloth for the LCD screen and keyboard, compressed air for getting dust out of the fan, and cleaning solution. It is also important to never use harsh chemicals such as bleach as they can cause damage to the laptop.[69]

Original external components are expensive, and usually proprietary and non-interchangeable; other parts are inexpensive—a power jack can cost a few dollars—but their replacement may require extensive disassembly and reassembly of the laptop by a technician. Other inexpensive but fragile parts often cannot be purchased separate from larger more expensive components.[70] The repair costs of a failed motherboard or LCD panel often exceed the value of a used laptop. Currently, parts can be ordered from third party vendors.

Laptops rely on extremely compact cooling systems involving a fan and heat sink that can fail from blockage caused by accumulated airborne dust and debris. Most laptops do not have any type of removable dust collection filter over the air intake for these cooling systems, resulting in a system that gradually causes it to conduct more heat and noise as the years pass. In some cases the laptop starts to overheat even at idle load levels. This dust is usually stuck inside, where the fan and heat sink meet, where it could not be removed by a casual cleaning and vacuuming. Most of the time compressed air can dislodge the dust and debris but may not entirely remove it. After the device is turned on the loose debris is rebuilt back up the cooling system by the fans. A complete disassembly is usually required to clean the laptop entirely. However, preventative maintenance such as regular cleaning of the heat sink via compressed air can prevent dust build up on the heat sink. Many laptops are difficult to disassemble by the average user and contain components that are sensitive to electrostatic discharge (ESD).

Battery life is limited because the capacity drops with time, eventually requiring replacement after as little as a year. A new battery typically stores enough energy to run the laptop for three to five hours, depending on usage, configuration, and power management settings. Yet, as it ages, the battery's energy storage will dissipate progressively until it lasts only a few minutes. The battery is often easily replaceable and a higher capacity model may be obtained for longer life. Some laptops (specifically ultrabooks) do not have the usual removable battery and have to be brought to the service center of its manufacturer to have its battery replaced. Replacement batteries can also be expensive.

Because they are valuable, common, and portable, laptops are prized targets for theft. Every day, over 1,600 laptops go missing from U.S. airports.[71] The cost of stolen business or personal data, and of the resulting problems (identity theft, credit card fraud, breach of privacy), can be many times the value of the stolen laptop itself. Consequently, physical protection of laptops and the safeguarding of data contained on them are both of great importance.

Most laptops have a Kensington security slot, which can be used to tether them to a desk or other immovable object with a security cable and lock. In addition, modern operating systems and third-party software offer disk encryption functionality, which renders the data on the laptop's hard drive unreadable without a key or a pass phrase. Some laptops also now have additional security elements added by the consumer, including eye recognition software and fingerprint scanning components.[72] Software such as LoJack for Laptops, Laptop Cop, and GadgetTrack have been engineered to help victims locate and recover a laptop in the event of theft.

In Robbins v. Lower Merion School District (Eastern District of Pennsylvania 2010), school-issued laptops loaded with special software afforded two high schools with the capability to take secret webcam shots of their students at home, via their students' laptops.[73][74][75]

Setting one's laptop with password on its firmware (Protection against going to firmware setup or booting), internal HDD/SSD (Protection against accessing it and loading operating system on it afterwards), and every user account of the operating system are additional security measures that (s)he should do.[76][77]

Laptop theft is a serious problem, with fewer than 5% of lost or stolen laptops ever recovered by the companies that own them.[78] However, that number may decrease due to a variety of companies and software solutions specializing in laptop recovery. For example, Lojack for Laptops is security software that includes an Investigations and Theft Recovery Team made up of ex law enforcement officers who locate and recover stolen laptops. The service utilizes persistent technology, which means it can't be removed or disabled by a thief. LoJack can only work to track down a missing laptop when it is turned on and it is connected to the Internet. The owner can also remotely delete files or lock their device, so no one can access their personal data.

There are a multitude of laptop brands and manufacturers; several major brands, offering notebooks in various classes, are listed in the box to the right.

The major brands usually offer good service and support, including well-executed documentation and driver downloads that will remain available for many years after a particular laptop model is no longer produced. Capitalizing on service, support and brand image, laptops from major brands are more expensive than laptops by smaller brands and ODMs.

Some brands are specializing in a particular class of laptops, such as gaming laptops (Alienware), high-performance laptops (HP Envy), netbooks (EeePC) and laptops for children (OLPC).

Many brands, including the major ones, do not design and do not manufacture their laptops. Instead, a small number of Original Design Manufacturers (ODMs) design new models of laptops, and the brands choose the models to be included in their lineup. In 2006, 7 major ODMs manufactured 7 of every 10 laptops in the world, with the largest one (Quanta Computer) having 30% of world market share.[79] Therefore, there often are identical models available both from a major label and from a low-profile ODM in-house brand.

Battery-powered portable computers had just 2% worldwide market share in 1986.[80] However, laptops have become increasingly popular, both for business and personal use.[81] Around 109 million notebook PCs shipped worldwide in 2007, a growth of 33% compared to 2006.[82] In 2008 it was estimated that 145.9 million notebooks were sold, and that the number would grow in 2009 to 177.7 million.[83] The third quarter of 2008 was the first time when worldwide notebook PC shipments exceeded desktops, with 38.6 million units versus 38.5 million units.[81][84][85][86]

May 2005 is the first time notebooks have outsold desktops in the US over the course of a full month; at the time notebooks sold for an average of $1,131 while desktops sold for an average of $696.[87]

When looking at operating systems, for Microsoft Windows laptops the average selling price (ASP) showed a decline in 2008/2009, possibly due to low-cost netbooks, drawing US$689 at U.S. retail in August 2008. In 2009, ASP had further fallen to $602 by January and to $560 in February. While Windows machines ASP fell $129 in these seven months, Apple(Mac) OS X laptop ASP declined just $12 from $1,524 to $1,512.[88]

The ruggedized Grid Compass computer was used since the early days of the Space Shuttle program. The first commercial laptop used in space was a Macintosh portable in 1991 aboard Space Shuttle mission STS-43.[89][90][91] Mac and other laptop computers continue to be flown aboard manned spaceflights though the only long duration flight certified computer for the International Space Station is the ThinkPad.[92] As of 2011 over 100 ThinkPads were aboard the ISS. Laptops used aboard the International Space Station and other spaceflights are generally the same ones that can be purchased by the general public but needed modifications are made to allow them to be used safely and effectively in a weightless environment such as updating the cooling systems to function without relying on hot air rising and accommodation for the lower cabin air pressure.[93]

Laptops operating in harsh usage environments and conditions, such as strong vibrations, extreme temperatures and wet or dusty conditions differ from those used in space in that they are custom designed for the task and do not use commercial off-the-shelf hardware.

A common accessory for laptops is a laptop sleeve, laptop skin or laptop case, which provides a degree of protection from drops, impacts, or scratches. Sleeves, which are distinguished by being relatively thin and flexible, are most commonly made of neoprene, with sturdier ones made of LRPu (low-resilience polyurethane), with some wrapped in ballistic nylon to provide some measure of waterproofing. Bulkier and sturdier cases can be made of metal with polyurethane padding inside, and may have locks, for added security.

Another common accessory is a laptop cooler. This device helps lower the internal temperature of the laptop by using either active or passive methods. A general active method is plugging a laptop cooler into the laptop and using fans to draw heat away from the laptop. A common passive method is just propping the laptop up on some type of pad so it can receive more air flow.

^In a comparison between laptop and desktop of equal cost, the desktop's System Benchmark Score was twice that of the laptop. "What to Buy, a Notebook or Desktop PC?". Tom's Hardware. 11 June 2008. Retrieved 28 November 2008.

^For example, a review of the MSI Wind Netbook says that "The device is rarely sluggish in general use. It renders Web pages quickly, launches most applications without becoming too bogged down and generally doesn't feel like it's a budget laptop." Reid, Rory (7 July 2008). "MSI Wind Review". CNET Australia. Retrieved 28 November 2008.

^For example, the video display cable and the backlight power cable that pass through the lid hinges to connect the motherboard to the screen will eventually break from repeated opening and closing of the lid. These tiny cables usually cannot be purchased from the original manufacturer separate from the entire LCD panel, with the price of hundreds of dollars, although for popular models an aftermarket in pulled parts generally exists.

^[2], Ponemon Institute, Airport Insecurity: The Case of Lost Laptops, June 2008